Expression of transfected recombinant oncogenes increases radiation resistance of clonal hematopoietic and fibroblast cell lines selectively at clinical low dose rate.

To determine the effect of oncogene expression on gamma radiation sensitivity of hematopoietic compared to fibroblastic cells, we selected clonal sublines of an interleukin-3 (IL-3)-dependent hematopoietic progenitor cell line 32D cl 3 and NIH/3T3 embryo fibroblastic cells following transfection with each oncogene linked to the mycophenolic acid resistance gene. Each mycophenolic acid-resistant subclone demonstrated high levels of specific poly(A)+ mRNA for each oncogene. The parent line 32D cl 3 demonstrated similar radiosensitivity at 116 cGy/min (D0 126, n 1.

Dose perturbations at interfaces in photon beams: secondary electron transport.

An improved, quantitative version of the partial fluence model [Med. Phys. 14, 585 (1987)] for the calculation of dose perturbations at media interfaces in photon beams is presented and compared with measurements made at interfaces between polystyrene and materials ranging in atomic number from aluminum to lead, for photon beams ranging in energy from 60Co to 24 MV.

Validity of transition-zone dosimetry at high atomic number interfaces in megavoltage photon beams.

Measurement of dose or dose perturbation factors at high atomic number interfaces are usually performed with a thin-window parallel-plate ion chamber. In a transition region, under nonequilibrium conditions, accuracy of ion chamber readings for the dose measurements has often been questioned. This paper critically analyzes the factors (stopping power ratio and charge collection) for the dose measurements at interfaces.

Backscatter dose perturbation at high atomic number interfaces in megavoltage photon beams.

Most computer algorithms used clinically for photon beam treatment planning are unable to predict the effect of electron backscattering on dose distribution from high atomic number materials. It has been observed that there is a significant dose enhancement at such an interface. We define the dose enhancement in terms of backscatter dose factor (BSDF), which depends on the energy of the photon beam, thickness and width of the inhomogeneity, distance from the interface, and the atomic number of the inhomogeneity.

Dose distributions in regions containing beta sources: large spherical source regions in a homogeneous medium.

The energy averaged Boltzmann equation model is applied to the determination of dose distributions in infinite, homogeneous media with uniform, monoenergetic, isotropic source distributions in spherical regions of radius larger than the electron range. The generalization to the case of spherically symmetric source distributions is made. Comparisons with dose distributions calculated by the integration of dose point kernels derived from Monte Carlo calculations are presented.

Stimulation of inositol phosphate production by propranolol in human neutrophils.

1. Propranolol has been reported to be beneficial in treating patients suffering from a variety of diseases including migraine, psychosis and schizophrenia. The mode of action of propranolol in the treatment of the above diseases is not clear.

Evaluation of several film/screen combinations for megavoltage radiation therapy treatment field verification.

The introduction of a lower cost alternative to a film commonly used for megavoltage radiation therapy port films led to a comparison of two films (Kodak X-TL and X-OMAT G) in four metal screen cassette configurations. In addition to determination of H-D curves and point spread functions, images of humanoid phantom sections were obtained and evaluated for clinical "usefulness." The X-OMAT G film-screen combinations compared favorably with the X-TL film combinations with respect to the H-D Curves and point spread functions but there was a slight preference for X-TL film.

Interface dose perturbation as a measure of megavoltage photon beam energy.

The description of the quality of a photon beam has usually been characterized by a single value such as the half-value layer, the effective attenuation coefficient, the percent depth dose, and most recently by the ionization ratio (IR). Although the IR is simple and easy to measure, it lacks sensitivity at photon energies above 10 MV. This paper describes a method based on dose perturbation at an interface and defines the forward dose perturbation factor (FDPF) as a measure of beam quality.

An empirical method for beta-ray dosimetry at a homogeneous plane interface.

A simple equation is presented for the dose calculation at a plane interface from monoenergetic beta sources distributed uniformly in a half space of an infinite water medium. The calculated dose distribution is accurate to within 1.2% of Monte Carlo data for energies ranging from 0.

The production of secondary electrons in an electron beam.

Convenient methods for calculating the ratio of restricted to unrestricted collision stopping power in water over a wide range of initial and cutoff energies, the rate of production of secondary electrons, and the primary electron dose distribution in an electron beam, are presented.

Dose distributions in regions containing beta sources: plane interface in a homogeneous medium.

An analytic model to calculate dose distributions in regions containing beta sources is developed along with a solution for the dose distribution in an infinite, homogeneous medium in which there is a uniform, monenergetic, isotropic source distribution on only one side of a plane. Comparisons with published Monte Carlo calculations are made.

Inhibitory action of spermidine on formyl-methionyl-leucyl-phenylalanine stimulated inositol phosphate production in human neutrophils.

The effect of the polyamine, spermidine, on formyl-methionyl-leucyl-phenylalanine stimulated hydrolysis of polyphosphoinositides was examined in purified human neutrophils by measurement of inositol phosphate production from radioactively labelled inositol. Spermidine inhibited formyl-methionyl-leucyl-phenylalanine stimulated inositol phosphate production by neutrophil in a dose dependent manner. Inhibition of formyl-methionyl-leucyl-phenylalanine stimulated inositol phosphate accumulation by spermidine was maximal at 10 microM and the IC50 value for this effect was 4.

Dose perturbations at interfaces in photon beams.

A model based on an approximation called the partial fluence approximation is presented for the calculation of dose distributions in the vicinity of medium interfaces in photon beams. The predictions of the model are compared with dose distributions measured in layered phantoms consisting of aluminum and polystyrene, for photon beams ranging in energy from 60Co to 24 MV.

Evaluation of colposcopy in the screening of pre-malignant and malignant lesions of uterine cervix.

In an attempt to evaluate the effectiveness of colposcopy in screening pre-malignant and malignant lesions of uterine cervix, one hundred cases of atypical colposcopical findings were cytologically and histologically analysed along with one hundred individuals with typical colposcopical appearance. It was observed that moderate dysplasia, severe dysplasia and malignant lesions of uterine cervix reveal certain distinct changes in the colposcopic "Transformation Zone" which are well related to the cytological and histological findings. The results suggested that colposcopy might be undertaken as a rapid, reliable and complementary tool for cancer screening in a vastly populated country like India.

Abnormal membrane composition and membrane-dependent transduction mechanisms in cluster headache.

Previous studies have indicated that membrane structure and function may be abnormal in cluster headache. This has been further investigated by analysis of membrane phosphatidylcholine, total phospholipids, and cholesterol in erythrocytes and by assay of receptor-mediated transduction. The stimulation of lymphocyte adenylate cyclase with isoprenaline and prostacyclin was used as the test system.

Determination of free choline in plasma and erythrocyte samples and choline derived from membrane phosphatidylcholine by a chemiluminescence method.

A sensitive chemiluminescence method for assay of choline which has been developed for analysis of erythrocyte and plasma levels of choline is reported here. This method includes a charcoal purification step which yields consistent results with plasma and erythrocyte extracts. Further, choline derived from membrane phosphatidylcholine may also be measured by an extension of this method following digestion with phospholipase D.

Raised C-reactive protein levels in serum from smokers.

Investigation of a possible quantitative relationship between the extent of tissue injury due to inhalation of tobacco smoke and changes in concentrations of a number of acute phase proteins were studied in smokers. Smokers showed an acute phase response as indicated by significantly raised serum C-reactive protein levels. Significant lowering of serum albumin levels was also observed in smokers.

Effects of zinc deficiency on ethanol metabolism and alcohol and aldehyde dehydrogenase activities.

Alcohol dehydrogenase, low Km and high Km mitochondrial and microsomal aldehyde dehydrogenase, and in vivo ethanol elimination rates were determined in five groups of male Sprague-Dawley rats given liquid diets, as follows: control (C), control plus 5% ethanol (CE), pair-fed control and zinc-deficient (PC-ZnD), zinc-deficient (ZnD), and zinc-deficient plus 5% ethanol (ZnDE). Rats fed CE had decreased liver and serum zinc content. The animals given ZnD diets had an even more dramatic decrease in their tissue zinc concentrations and displayed marked growth retardation.

Erythrocyte choline concentrations and cluster headache.

Erythrocyte choline concentrations were measured in patients with cluster headache and age related control subjects. Concentrations were significantly reduced in the patients with headache both during a cluster period and between clusters, being 58% and 55% of the control value, respectively. After two weeks' treatment with lithium, choline concentrations in the patients with cluster headache increased to 78 times the control value (mean 369.

Bronchorrhoea--separation of mucus and serum components in sol and gel phases.

Bronchorrhoea sputum separates into two phases--sol and gel--at low speed centrifugation (5000 g), although higher speed (160 000 g) is required to obtain complete separation. Markers of mucus glycoprotein and serum transudate have been estimated in sputum, sol, and gel in five cases of bronchorrhoea associated with chronic bronchitis, asthma, or alveolar cell carcinoma. In all samples markers of both mucus glycoprotein and serum component were present in each phase.

Pus, deoxyribonucleic acid, and sputum viscosity.

On 100 sputum specimens selected from patients suffering from chronic bronchitis, bronchiectasis, asthma, and cystic fibrosis total deoxyribonucleic acid (DNA) content has been related to macroscopic type, to total dry weight yield, and to the apparent viscosity of the secretion at 1350 s-1: since DNA may be present, either as fibres or within cells, in one-third of the specimens the contribution of each form to the apparent viscosity was assessed. The effect on sputum viscosity of the addition of DNA in vitro has also been studied. Whereas between mucoid, mucopurulent, and purulent macroscopic types a significant difference in total DNA and dry weight yield has been found, viscosity was not significantly correlated with purulence.

An assessment of the effect of hormone and neurotransmitters on adenine and guanine derivatives simultaneously in rat brain cortical slices.

A A 2-dimensional thin-layer method has been developed for the separation on cellulose of adenine and guanine derivatives. Using incubated rat cerebral cortex slices it was shown that noradrenaline and acetylcholine stimulated cAMP and cGMP production respectively but glutamate and gamma-aminobutyric acid stimulated production of both cyclic nucleotides.